An image sensor irradiates an object to be read using irradiation light emitted by a light source incorporated in a casing, and light reflected by the object to be read is focused through a focusing optical system, such as a lens, onto a photoelectric conversion element, and image data is obtained (for example, see Patent Literature 1).
In the image sensor described in Patent Literature 1, sensor ICs are lined in a linear manner on a sensor board that is fixed to a sensor frame by fixing members such as screws.